For example, as disclosed in Patent Document 1, iron cores which are each formed of divided pieces (split cores) are manufactured as follows. That is, split core pieces are manufactured by stamping a steel plate using a press die, and the plurality of split core pieces are laminated and fixed by crimping, whereby an iron core is manufactured. Stator iron cores are each manufactured as follows. That is, a coil is wound around a magnetic pole tooth of each split core having an insulation sheet interposed therebetween, split cores having the coils wound around are assembled annularly, and the annularly assembled split cores are fixed in a frame.
The split cores can be wound around separately, and thus as compared to a case of winding around an integrated iron core which is not divided into pieces, a sufficient space is secured for a nozzle for winding coils to pass through, and coils can be mounted in the high density. Thus, such designing as improvement in torque by increasing the number of turns of coil, and reduction in electric resistance by employing coils having a large cross-sectional area can be achieved, and consequently, the performance of motors in terms of torque, efficiency and the like can be advantageously improved.
[Patent Literature]
    [Patent Literature 1] Japanese Patent No. 3461552 (Page 3, FIG. 1)